William Elliot <marsh@panix.com> wrote innews:Pine.NEB.4.64.1307252033010.24715@panix3.panix.com:

> How do we find the shortest distance between two lines L, L' in R^3

Each line has a direction vector. The cross product n of the twodirection vectors is perpendicular to both lines. Pick a pointon each line, P and Q. The projection of the vector from P to Qonto the vector n is the distance.